﻿/*
 * Copyright (c) 2011, Andrey Krupa
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Krupa.Pro nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS 
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE 
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */
using System;
using System.IO;
using System.Web;
using System.Web.Mvc;

namespace Krupa.Pro.Web.Utility.Processors
{
    public class CustomTextPostProcessingAttribute : ActionFilterAttribute
    {
        public override void OnResultExecuting(ResultExecutingContext filterContext)
        {
            filterContext.HttpContext.Response.Output = new ProxyWriter(filterContext.HttpContext.Response.Output);
            base.OnResultExecuting(filterContext);
        }

        public override void OnResultExecuted(ResultExecutedContext filterContext)
        {
            var proxy = HttpContext.Current.Response.Output as ProxyWriter;
            if (proxy != null)
            {
                var data = proxy.GetStringBuilder().ToString();

                HttpContext.Current.Response.Output = proxy.ResponseWriter;

                proxy.Dispose();
                if(!filterContext.Canceled && (filterContext.Exception == null || filterContext.ExceptionHandled))
                {
                    ProcessData(data, HttpContext.Current.Response.Output);
                }
            }
            base.OnResultExecuted(filterContext);
        }

        private class ProxyWriter : StringWriter
        {
            public ProxyWriter(TextWriter writer)
            {
                ResponseWriter = writer;
            }

            public override void Flush()
            {
                throw new InvalidOperationException("Stream cannot be flushed during custom text postprocessing");
            }

            public override void Close()
            {
                throw new InvalidOperationException("Stream closed unexpectedly during custom text postprocessing");
            }

            public TextWriter ResponseWriter { get; private set; }
        }


        protected virtual void ProcessData(String data, TextWriter targetWriter)
        {
            targetWriter.Write(data);
        }

    }
}